Improvement in indicators for steam-engines



l. W4. THOMPSON.

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NPETERS, FHOTO-LITHOGRAFUER. WASHINGTON, D-C

UNITED STATES PATENT EEICTEL JOSEPH THOMPSON, OF JSALEM, OHIO, ASSIGNOR TO HIMSELF AND BUOKEYE ENGINE COMPANY, -OF SAME PLAGE.

IMPROVEMENT IN INDICATORS FOR STEAM-ENGINES.

Specification forming part of Letters Patent No. 167,364, dated August 431, 1875; application tiled August 13, 1875.

do hereby declare that the following is a full,

clear, and exact description of the same, reierence being had to the accompanying drawing forming a part of this specification, in Which- Figure l is a sectional elevation of my improved indicator, and Fig. 2 a similar vieW of the drum or paper-carrying barrel and its contained spring and tension-adjusting devices .l

said link, therefore, constitutes a movable fultherefor.

The indicator is designed to register the relative amounts ot steam-pressure exerted on the piston at each portion of itsstroke. It is, in part, an improvement upon the automatic recording-indicator for which Letters Patent of the United States were granted to C. B. Richards, March 24,1863, No. 37,980.

The object of the invention is chietly to reduce the number and weight ot' the parts composing Richards recording mechanism proper, and thus correspondingly reduce their momentum when iu action, to the end or" securing a more perfect record ofthe several steampressures existing in the engine-cylinder during a given stroke or strokes ot' the piston. This reduction in momentum is particularly important in relation to quick-stroke engines for the indication given or delineation made on the paper barrel by the markingpoint will be more or less imperfect as the momentum of the moving parts is greater or less.

In carrying out my invention I dispense with a separate holder for, the pencil by which the record is made on a drum or paper barrel, and attach the pencil directly to the main lever, to which a vertical vibratory movement is imparted by the reciprocatiou of the spring-piston under the varying pressure of steam in the cylinder. To preserve the desired parallel movement, I pivot the Working or marking lever to a movable or oscillating fulcrum, connect its free end to a fixed standard by means of a link or bar, and pivot it iuternlediately of said fulcrum and link directly to the piston-rod, which latter is necessarily vibrated at each movement of the piston. The invention further includes a compensating connection or joint between the piston-rod and piston, and the means t'or adjusting` the tension of the spring ot' the drum upon which the record is made, all as hereinafter more fully described.

'The piston A works in a tube, B, which is in immediate communication with the enginecylinder.. The piston-rod C is pivoted to the working-lever D, which has a socket in its free end to receive a pencil, a, and is pivoted at ythe other end to a link, E, hinged to tube B. The

crum, oscillating freely in the lengthwise direction of the marking-lever D, whenever the piston A changes its position by reason of variation in steam-pressure. To preserve the desired parallel movement, and cause the pencil to move in a straight line over the paper barrel, I connect the lever D to a xed vertical standard, F, by a link, b, pvoted to the lever at a point near the piston-rod, and between it and the pencil a. It is evident that since the lever D has a lengthwise reciprocation (as Well as vertical vibration) at every movement of the pistou up or down, the upper end of the piston-rod must vibrate correspondingly in the arc of a circle whose radius is determined by the extent ot' such movement of the pistou. It is hence necessary to have a lieXible connection between the rod and piston. To this end I arrange the piston-rod to Work in a tube or trunk, G, (as in truuk-engiues,) Which slides through the head H of tube B. Said trunk screws on the end of piston-stem I, and has a concavity or socket thereat suitable to receive the head ot the piston-rod. The latter is rounded or spherical on its upper side corresponding to the socket of trunk G, and has a concavity in its underside corresponding to the conical head oi' a small stud, c', which is screwed into rthe end ot' the main piston-stem I, as shown. The 4parts are thus firmly connected by a compensating-joint, which has the freedom of movement required for the piston-rod. The trunk G and stem I ofthe piston Aare encircled by a spiral spring, K, Whose tension must be overcome by the steam-pressure to produce an upward movement of the piston. The vertical pivoted barrel L is provided with the usual form of paper-holding` device M` and is caused to make partial rotations back and forth coincident With the movement of the piston of the engine, by means of a cord or other suitable means of connecting it With some reciprocating part of the engine, substantially as in Richards7 indicator. The drum is supported by stem or standard N, which rises vertically from a lateral arm of the tube B. The coiled spring O is arranged in the case P, which is xed on the tubular stem Q of the barrel L. The top ot' the case N is formed by a disk, R,

. having a hub, c, which turns loosely on the standard N. The tension of the spring can be adjusted at will by turning and clamping the disk R, by means of nut S, on the upper end of standard N, the hub c of said disk vand the inner side ot' the case having each a lug, 0, with which the' ends of the spring are 'in contact. The spring-case accurately fits the drum, and thus forms one of the bearings or sup ports therefor.

In part recapitulating, it will be seen that When the steam-pressure in the engine-cylinder increases, the piston A will rise, and when it decreases the piston will fall. in either case causing a vibration of the lever D, so that the pencil is caused to move over the paper barrel L in a straight line, and faithfully record the -limits of variation of such steampressure. Simultaneously with this movement of the pencil the barrel L makes corresponding reciprocatingmovements, so that the variation during each stroke of the piston is clearly recorded.

The construction and arrangement of the marking device is such that the inertia and corresponding momentum are greatly reduced, and greater accuracy and reliability therefore secured. The spring tension device is easily accessible, and may be quickly adjusted to vary the quickness of the return movement of the paper barrel.

Having thus described my invention, what I claim :is-

l. In a steam-pressure recorder, the combination, With the Working-lever, carrying the marker, of a movable fulcrum, a fixed standard, F, and link b, connecting the lever directly to the standard, substantially as shown and described, for the purpose specied.

2. In a steam-pressure recorder, the combiation with the reciprocating drum of the spring O, spring-case, the disk having hub c, and clamping screw-nut S, all as shown and described, to permit the spring tension to be adjusted as desired.

3. rI he combination of rod O and stud c', having corresponding concavity and conveXity, and the screw-socket for connecting` said parts O t' to the piston or movable part, to form a a universal compensating-joint, as shown and described.

JOSEPH W. THOMPSON Witnesses:

GHAs. BOONE, PETER AMBLER.' 

